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Chemical Methods of Vector Control
Published in Jacques Derek Charlwood, The Ecology of Malaria Vectors, 2019
Insecticides are delivered in a variety of ways including wettable powders (WPs), emulsifiable concentrates (ECs) and solution. There are four main classes of insecticide used in public health: Organochlorines such as DDT are inhibitors of the normal functioning of the nervous system.Organophosphates (phosphorothioates) such as pirimiphos-methyl (Actellic) act by binding the enzyme acetylcholinesterase at the nerve junction. Phosphorothioate insecticides can vapourise quickly and often have associated with them a sulphurous ‘bad egg’ smell.Carbamates such as bendiocarb have an identical mode of action to the organophosphates.Pyrethroids such as deltamethrin act in exactly the same way as DDT and its analogues.Insect Growth Regulators may be used against the larval stages of the mosquito.
Rationale and technique of malaria control
Published in David A Warrell, Herbert M Gilles, Essential Malariology, 2017
David A Warrell, Herbert M Gilles
Bendiocarb, although applied at low dosages (active ingredient 0.4 g/m2) because of its high insecticidal activity, has a high mammalian toxicity. However, it is classed as a moderately hazardous insecticide with an LDW of 55 mg/kg. This is minimized by providing the 88g/kg (80 per cent) water-dispersible powder formulation in preweighed sachets: one sachet added to the water in the spray pump gives the required 10 g/L (1.0 per cent) spray suspension. Because bendiocarb is virtually odourless and does not leave an unsightly deposit, it is acceptable to householders. In a study in Zimbabwe, the insecticide remained active for up to 8 weeks (96 per cent mortality) on thatch, and in southern Mexico for up to 3 months on most common indoor house surfaces.
Supercritical Fluid Extraction as a Sample Preparation Tool in Analytical Toxicology
Published in Steven H. Y. Wong, Iraving Sunshine, Handbook of Analytical Therapeutic Drug Monitoring and Toxicology, 2017
Robert J. Maxwell, Janet F. Morrison
Researchers have used sorbent materials other than alumina and silica gel to retain fats in extraction vessels as a means of preventing their carryover into analyte collection traps. Murugaverl et al.79 developed a hyphenated SFE-SFC-MS for the total analysis of bendiocarb in bovine muscle. They found that most of the commonly used adsorbents could not completely retain fats on the inline sorbent beds, resulting in contamination of the SFC-MS segment of the system. This problem was eliminated by using a combination of normal- and reversed-phase sorbents (diol/C18, 7:93) for fat retention. This combination sorbent bed retained the fats completely, permitting the on-line detection of 1 ppm bendiocarb. Similarly, Alley and Lu80 conducted an extensive study to evaluate a series of adsorbents for their efficiency in retaining fats. Extraction vessels were packed first with 5 g of the adsorbent, followed by a mixture of the sample and sodium sulfate. The analysis of carp and chicken eggs using silica gel, amino-silica and Florisil adsorbents gave less than 0.1 mg co-extracted fat and recoveries of fortified PCB (Arochlor 1254) that ranged from 85 to 95%; three other adsorbents (alumina, C-18-silica, and CN-silica) gave 9 to 57% co-extracted fat.
Exposure to pesticides and oxidative stress in Brazilian agricultural communities
Published in Biomarkers, 2021
Aline de Souza Espindola Santos, Christine Gibson Parks, Mariana Macedo Senna, Leandro Vargas B. de Carvalho, Armando Meyer
Exposure to insecticides has been positively associated with CAT and SOD activities, and negatively associated with GST and GR activities and thiol levels in cross-sectional studies (Mecdad et al.2011, Ogut et al.2011). Zepeda-Arce et al. (2017) observed that the use of bendiocarb, a carbamate insecticide, and deltamethrin, a pyrethroid insecticide, were positively associated with GPx activity. In our study, deltamethrin use was negatively associated with GST activity, while the carbamate insecticide methomyl was positively associated with GR and GPx activities. Although speculative, these last results suggest that methomyl might be associated with an increased RO2H (Figure 1). Rats orally exposed to deltamethrin showed suppression of GPx, GST, and CAT activities in liver and kidney tissues (Rehman et al.2006, Sharma et al.2014). In animal models, subacute exposure to methomyl was associated with decreased GPx and GR activity in rat serum (Mansour et al.2017).